The present invention relates to new cyclic esterketone compounds which are useful as monomers for the production of polymers, to a process for the synthesis thereof and to a process for the preparation of poly(esterketone) polymers and to the poly(esterketone) polymers so obtained therewith.
In recent years there has been a strong preoccupation with the development of biodegradable and nontoxic polymers which may be used for replacing existing polymers. To be useful for such purposes, the polymers must also possess other properties of the polymers which they are intended to replace. Such properties include, inter alia, permeability, biocompatibility, promotion of bioadhesion and reactivity for attachment to drugs.
In this regard, various aliphatic polyesters derived from lactones have drawn interest. Of particular interest in this regard are those aliphatic polyesters derived from lactones and, in particular, those derived from xcex5-caprolactone. Polymers derived from xcex5-caprolactone (such polymers being referred to herein as Pxcex5-CL) are one of the very few commercially available biodegradable polymers, being well known for its biocompatibility, permeability and biodegradability. Pxcex5-CL also possesses the rare property of being miscible with a variety of other polymers (such as PVC), thereby permitting them to be formed therewith into polymer blends/alloys (e.g., copolymers) in which deficient properties of the other polymer(s), such as poor stress/crack resistance, gloss and adhesion, are ameliorated.
Pxcex5-CL has been as particularly desirable for the replacement of certain polymers, vinylic and otherwise in plastic bags and in films and wrappings. Unfortunately, due to a relatively low melting point of about 60xc2x0 C., the ability for Pxcex5-CL to be employed to replace such polymers in such uses is extremely limited, with an increase of at least 20xc2x0 C. being necessary.
To resolve the above-mentioned problems, a new polymer, (2-oxep ane-1,5-dione(also known, and referred to herein, as PKCL) has been synthesized which possesses a melting point of about 150xc2x0 C. and a glass transition temperature of about 41xc2x0 C. This polymer, is formed from the monomer 1,4,8-trioxaspiro[4,6-]-9-undecanone (also known as TOSUO) in a well-controlled xe2x80x9clivingxe2x80x9d ring-opening polymerization reaction using aluminum isopropoxide [A1(OiPr)3] as an initiator, whereby polyTOSUO is formed, followed by a reaction for 1 hour at 25xc2x0 C. using Ph3CBF4 and CH2Cl2, whereby PKCL is formed.
TOSUO is, in turn, synthesized according to a Baeyer-Villiger reaction by the oxidation of 1,4-cyclohexanedione monoethylene acetal by 3-chloroperoxybenzoic acid (m-CPBA) at 40xc2x0 C. in CH2Cl2. Unfortunately, the synthesis of TOSUO follows a pathway that requires separate steps, the first wherein the finctions of the ketone are shielded and the second wherein the acetal functions are deshielded, thereby complicating and increasing the cost and time required for the synthesis.
Accordingly, it can be seen that there remains a need to provide improved compounds which are useful as new monomers that may be polymerized to form poly(esterketone) polymers, which monomer compounds may also be directly synthesized from the starting material in high yield using a one-step process. It can further be seen that there remains a need to provide a process to form poly(esterketone) polymers from the monomer compounds, as well as a need to provide the poly(esterketone) polymers so obtained.
It is a first primary object of the present invention to provide new cyclic esterketone compounds which are useful as new monomers that may be polymerized to form poly(esterketones), in particular poly(oxepane-diones), more particularly poly(unsubstituted oxepane-diones) such as poly(2-oxepane-1,5-dione) (PKCL), so that said compounds may be used to replace TOSUO for use in producing PKCL.
It is a further object of the present invention to provide such a compound which may be easily obtained from the starting material in one-step.
It is a second primary object of the present invention to provide a process whereby the cyclic esterketone compounds of the present invention may be produced from the starting material in one-step.
It is a third primary object of the present invention to provide improved poly(esterketone) polymers.
It is a fourth primary object of the present invention, to provide a process for the preparation of poly(esterketone) polymers.
In accordance with the teachings of the present invention, disclosed herein are novel cyclic esterketone compounds which are useful as monomers for the production of poly(esterketone) polymers, in particular polyoxepane-diones, more particularly poly(unsubstituted oxepane-diones) such as poly(2-oxepane-1,5-dione) (PKCL). These compounds are also simple and easy to synthesize from their starting materials in high yield using a one-step process that involves the oxidation (and, particularly, mono-oxidation) of the starting material (and particularly, cyclic diketones, such as saturated cyclic diketones, more particularly cyclohexanediones, such as unsubstituted cyclohexanediones, for example 1,4-cyclohexanedione).
More precisely, disclosed herein are novel cyclic esterketones that are useful as monomers in the production of, e.g., PKCL. Preferably, these cyclic esterketones are chosen from appropriate oxepane-diones, namely unsubstituted oxepane-diones. Most preferred unsubstituted oxepane-dione is 2-oxepane-1,5-dione (referred to herein as KCL).
Unsubstituted oxepane diones particularly KCL) are particularly attractive compounds for use as monomers due to, inter alia, their long-term stability which translates into a good shelf life. In this regard, unsubstituted oxepane diones (particularly KCL) have a shelf-life, in open air at ambient temperature, of at least three months. Further, they may be conserved without substantial degradation for more than three months at xe2x88x9220xc2x0 C., in an inert nitrogen atmosphere. Such long-term stability is important in the measure where these compounds may be prepared in large quantities, with all the benefits that are derived from such an economy of scale.
Unsubstituted oxepane diones (particularly KCL) are further particularly useful due to the ease by which they may be synthesized in a one-step reaction by oxidation of the starting material.
In another aspect of the present invention, disclosed herein is a process for the synthesis of the novel cyclic esterketone compounds of the present invention, and in particular of 2-oxepane-1,5-dione (KCL), that permits the compound to be easily and simply prepared directly from the starting material in one, step.
The process of the present invention for the synthesis of unsubstituted oxepane diones (particularly of KCL) permits these (monomer) compounds to be easily and simply prepared in one-step directly from the starting material. In other words, the (monomer) compounds of the present invention (more particularly, 2-oxepane-1,5-dione) are obtainable by this process of the present invention.
In particular, the process of the present invention involves the oxidation (e.g., mono-oxidation) of cyclic diketones (to esters) to produce cyclic esterketone monomers according to the invention. Preferably, these cyclic diketones are saturated cyclic diketones. Cyclohexanediones are specially recommanded such as unsubstituted cyclohexanediones. Most preferred is 1,4-cyclohexanedione (which is used to synthesize KCL).
As will be readily understood (and as is capable of being determined) by one skilled in the art, the precise concentration of the starting material to be employed in the process of the present invention may be varied as needed to obtain the precise quantities of the (monomer) compounds of the present invention desired.
Nonetheless, it is contemplated herein that at least 0.01 M of starting material will be employed in the process of the present invention. Preferably, at least 0.06 M of starting material will be employed in the process of the present invention. Also preferred is the use of at least about 0.14 M of starting material. Still further preferred is the use of at least about 0.17 M of starting material. Most preferred is the use of at least about 0.2 M of starting material. In this regard, use of concentrations of 0.33 M, 0.55 M, 0.85 M and 0.99 M of starting material in the process of the present invention are particularly preferred.
As used herein, the symbol xe2x80x9cMxe2x80x9d, when referring to concentrations (of, e.g., starting material, oxidant, catalysts, initiators, etc.), is used to stand for molarity (moles of the substance per liter of the solution).
Preferably, the cyclic diketones useful in the present invention are oxidized (mono-oxidized) (to esters) by an oxidant that is, preferably, a peracid. This is especially the case where 1,4-cyclohexanedione is the cyclic diketone and the compound (i.e., monomer) desired to be obtained is 2-oxepane-1,5-dione (KCL).
In this regard, it is preferred that the peracid is a perbenzoic acid or a chloroperacid. Particularly preferred in this regard is that the chloroperacid is chloroperbenzoic acid. Most preferred is that the chloroperbenzoic acid is meta-chloroperbenzoic acid.
The precise peracid chosen may be any which is suitable for the task as can be determined by one skilled in the art. However, it is contemplated herein that where 1,4-cyclohexanedione is used to synthesize KCL, use of a meta-chloroperbenzoic acid is most preferred.
It is contemplated herein that the oxidant to be used to oxidize (mono-oxidized) the starting material may be generated xe2x80x9cin-situxe2x80x9d. This is particularly the case when the oxidant is a peracid.
In order to generate the oxidant (e.g., peracid) xe2x80x9cin-situxe2x80x9d, it is contemplated herein that an aldehyde will be provided which will be reacted (in-situ) with oxygen (O2).
An example of such an instance is addition of benzaldehyde (PhCHO) and oxygen to the starting material. In such a case, the oxygen reacts with the benzaldehyde to generate the peracid oxidant (perbenzoic acid) which then oxidizes the starting material. Another example is the addition of either a para-, ortho- or meta-chlorobenzaldehyde and oxygen to the starting material to generate, respectively, para-, ortho- or meta-chloroperbenzoic acid.
In such cases, the aldehyde is added as such and the oxygen is bubbled into the reaction medium by the use of any known apparatus which are well-known and used in the art for such a purpose.
As will be readily understood (and as is capable of being determined) by one skilled in the art, the precise concentration of the peracid or, in the event that xe2x80x9cin-situxe2x80x9d generation of the peracid is desired), the aldehyde and the oxygen to be employed in the process herein varies depending upon the precise starting material, peracid, etc., which is used.
Nonetheless, it is contemplated herein that for every mole/liter (M) of starting material employed in this process, at least 1 mole/liter (M) of peracid will also be employed. Preferably, at least 1.1 M of peracid will be employed for every 1.0 M of starting material employed in the process of the present invention. Further preferred is the use of at least about 2.0 M of peracid will be employed for every 1.0 M of starting material. Still further preferred is the use of at least about 3.0 M of peracid will be employed for every 1.0 M of starting material.
It is further preferred that no more than about 3.0 M of peracid for every 1.0 M of the starting material be used in the process of the present invention.
In the process for the synthesis of the novel monomer compounds of the present invention, the precise conditions and times under which the, oxidation of the starting material is performed may be optimized according to the starting material used, the monomer compound desired and/or the concentrations thereof, as may be determined by one skilled in the art.
Nonetheless, as to time, it is contemplated herein that oxidation of the starting material will be. carried out for at least about 10 minutes. It is further contemplated herein that oxidation of the starting material will be carried out for up to about 48 hours. However, it should be understood that, if desired or needed, the process may be carried out for periods of less than 10 minutes and/or for more than 48 hours.
As to temperature, it is contemplated herein that oxidation of the starting material will be carried out at a temperature of at least about 0xc2x0 C. It is further contemplated herein that oxidation of the starting material will be carried out in temperatures of up to about 120xc2x0 C. However, it should be understood that, if desired or needed, the process may be carried out in temperatures of less than 0xc2x0 C. and/or more than 120xc2x0 C.
It is contemplated that the preferred operating conditions will be to carry out oxidation of the starting material for about 1 hour to about 24 hours at a temperature in the range of about 20xc2x0 C. to about 80xc2x0 C. Particularly preferred is to carry out oxidation of the starting material at about 40xc2x0 C.
It is further preferred that oxidation of the cyclic diketones to form the monomer compounds according to the process of the present invention be carried out in the presence of a solvent. The solvent which is chosen for the synthesis of the monomers of the present invention may also be anyone which is suitable for the task as can be determined by one skilled in the art. Particularly preferred in this regard are dichloromethane and 1,2-dichloroethane.
Finally, it is noted that it is preferred that the oxidation of the cyclic diketones, and in particular of the unsubstituted cyclohexanediones (more preferably the 1,4-cyclohexanedione), according to the process of the present invention be done under the action of a catalyst. Examples of catalysts which would be useful in this regard are Ni(acac)2, Ni(dmp)2 which stands for bis-(dipivaloylmethanota)nickel (II) (ref: Yamada, T.; Takahashi, K.; Kato, K.; Takai, T.; Inoki, S.; Mukaiyama, T. Chem. Lett. 1991, 641), Ni(OAc)2, Cu(OAc)2 (ref: Bolm, C.; Schlingloff, G.; Weickhardt, K. Tetrahedron Lett. 1993, 34, 3405), heteropolyoxometalates (ref: Hamamoto, M.; Nakayama, K.; Nishiyama, Y.; Ishii, Y. J. Org. Chem. 1993, 58, 6421), iron (III) oxide, cobalt(p) oxide (ref: Li, X.; Wang, F.; Zhang, H.; Wang, C.; Song, G. Synth. Commun. 1996, 26, 1613). I this regard, it is preferred that the catatyst be iron (III) oxide.
The precise catalyst(s) to use and the precise concentration thereof to employ in the process of the present invention will vary depending upon various factors as will be readily understood by one skilled in the art.
In still another aspect of the present invention, disclosed herein is a (polymerization) process for the preparation of polymers, and in particular of polyesterketones, such as poly(oxepane-diones), preferably poly(unsubstituted oxepane-diones) and more preferably PKCL which can be used to replace Pxcex5-CL. This process is characterized by the polymerization of cyclic esterketone compounds, in particular of oxepane-diones, most particularly of the unsubstituted oxepane-diones of the present invention, and most particularly of 2-oxepane-1,5-dione.
This process may be either a solution polymerization process or a mass polymerization process, as desired and as can be readily decided on and determined by those skilled in the art.
In the polymerization process of the present invention, the polymerization of the cyclic esterketone (particularly the oxepane-dione, such as an unsubstituted oxepane-dione, in particular, of 2-oxepane-1,5-dione), can be promoted by any type of initiator known in the art. Particularly attractive are metal alkoxides, the metal of which contains free p, d or f orbital of a favorable energy, e.g., Mg, Ti, Zr, Zn, Sn, Al, Y, La, Hf and rare earth atoms, such as Sm.
Preferably, aluminum isopropoxide [Al(OiPr)3] is employed as an initiator in the polymerization process of the present invention.
As will be readily understood (and as is capable of being determined) by one skilled in the art, the precise concentration of the initiator to be employed in the process of the present invention may be varied as needed to obtain the polymer(s) which is (are) desired to be obtained thereby. In this regard, the concentration of the initiator to employ is defined by the molecular mass which is desired to be possessed by the polymer obtained therefrom.
In the polymerization process of the present invention, the polymerization can be promoted by any type of catalyst known in the art. Particularly attractive are metal oxides, halides or carboxylates, the metal of which contain free p, d or f orbital of a favorable energy, e.g., Mg, Ti, Zr, Zn, Sn, Al, Y, La, Hf and rare earth atoms, such as Sm. in the presence of protic species, such as alcohols, amines, thiols and water.
It is further preferred that such polymerization process employes Sn[OC(O)xe2x80x94CH(CH2xe2x80x94CH3)xe2x80x94(CH2)3xe2x80x94CH3]2 (herein referred to as stannous octoate) as a catalyst.
As will be readily understood (and as is capable of being determined) by one skilled in the art, the precise concentration of the catalyst to be employed in the process of the present invention may be-varied as needed to obtain the polymer(s) which is (are) desired to be obtained thereby.
It is further contemplated herein that in the polymerization process of the present invention, the polymerization may further be promoted by the use of any type of the aforementioned catalysts/initiators both in solution with apolar to medium polarity solvents, and in bulk (without any solvent).
The precise operating conditions and times to employ in the polymerization process of the present invention may be readily determined and optimized by one skilled in the art according to the process employed, the concentration of the starting material employed therein, the polymer desired and/or the quantities thereof.
Nonetheless, it is contemplated herein that the polymerization process of the present invention, be done at a temperature which is at least 0xc2x0 C. It is further contemplated herein that the polymerization be done at a temperature which is at least 20xc2x0 C. Further in this regard, it is also contemplated herein that the polymerization be done at a temperature of up to about 180xc2x0 C. It is further contemplated herein that the polymerization be done at a temperature of up to about 120xc2x0 C.
However, as will be readily understood by one skilled in the art, it should be understood that, if desired or needed, the polymerization process of the present invention may be carried out at temperatures of less than about 0xc2x0 C. and/or at temperatures of greater than about 180xc2x0 C.
In yet another aspect of the present invention, disclosed herein is a poly(esterketone) polymer which is obtainable by (and which has been obtained by) the polymerization process of the present invention.
The poly(esterketone) polymers according to the present invention, particularly poly(oxepane-dione) polymers such as poly(unsubstituted oxepane-dione) polymers, preferably PKCL are particularly useful polymers for replacing, in particular, PVC in films, wrapping and garbage bags. In this regard, it is noted that these poly(esterketone) polymers have a melting point of about 156xc2x0 C. and a glass transition temperature of about 41xc2x0 C. Accordingly, these polymers may be used in wide variety of applications in which Pxcex5-CL, due to it""s low melting point (about 60xc2x0 C.) cannot.
Unless specifically otherwise stated, as used herein, the terms xe2x80x9cpolymerxe2x80x9d and xe2x80x9cpolymer resinxe2x80x9d are used to refer to and include homopolymers, copolymers, terpolymers, etc., and blends and alloys thereof.
Unless specifically otherwise stated, as used herein, the term xe2x80x9ccopolymerxe2x80x9d refers to those polymers which are formed from two different monomers and includes block, graft, random and alternating polymers and blends and alloys thereof. In this regard, the polymer which comprised the copolymer may be either formed together, such as when at least two different types of monomers are polymerized at the same time and in the same reactor (commonly referred to as copolymerization) or they may be formed separately and mixed together either with or without reactivity therebetween.
If desired, the poly(esterketone) polymers of the present invention may be formed as copolymers (including but not limited to terpolymers) by either polymerization with at least one other monomer or by mixing (with or without chemical reactivity therebetween) of polymers which have been synthesized individually (e.g. by mixing in the presence of a transesterification catalyst, such as dibutyl tin oxide). Preferred poly(esterketone) copolymers of the invention are copolymers of KCL with at least one other monomer. Preferably, the at least one other monomer includes xcex5-CL. Other types of monomers/polymers which may be combined with KCL (either with random or sequential comonomer distribution) include but are not limited to lactides, glycolides, xcex2-, xcex3-, xcex4- and xcex5-lactones, substituted or not and their polymers.
In this regard, copolymers of KCL and xcex5-CL are particularly contemplated as being preferred.
Preferably, such PKCL-xcex5-CL) copolymers have at least about 1% (w/w) KCL. More preferred is that such P(KCL-xcex5-CL) copolymers have at least about 5% (w/w) KCL. Most preferred in this regard is that such P(KCL-xcex5-CL) copolymers have at least about 8% (w/w) KCL.
Further preferred is that such PKCL-xcex5-CL) copolymers have no more than about 99% (w/w) KCL. More preferred is that such PQ(CL-xcex5-CL) copolymers have no more than about 80% (w/w) KCL. Most preferred in this regard is that such P(KCL-xcex5-CL) copolymers have no more than about 50% (w/w) KCL.
The PKCL copolymers according to the invention [particularly the P(KCL-xcex5-CL) random copolymers] provided for by the process of the present invention have both a high melting point (ranging from about 80xc2x0 C. to about 150xc2x0 C.) and a low glass transition temperature (ranging from about xe2x88x9220xc2x0 C. to about 35xc2x0 C.).